Table 1. Theoretically Evaluated Free Energy Differences (ΔG, in kcal·mol^–1) for Critical Structures along the Reaction Paths–the First Transition State (TS1) and the σ-Complex Intermediate—for Chlorination of Monosubstituted Benzenes with Cl₂ in Water Solvent with Comparison to Experimental Data^a.

X	isomer	TS1	σ-complex	exp.b
OCH3	o-	0.1	3.1	0.8
	m-	9.1	19.8	-
	p-	0.0	0.0	0.0
CH3	o-	0.6	0.6	0.0
	m-	3.2	4.8	2.8
	p-	0.0	0.0	0.2
F	o-	1.2	2.7	1.3
	m-	5.5	8.4	-
	p-	0.0	0.0	0.0
Cl	o-	0.1	2.0	0.4
	m-	3.7	5.7	-
	p-	0.0	0.0	0.0
CF3	o-	1.5	2.0	1.4
	m-	0.0	0.0	0.0
	p-	2.3	2.4	1.8
CN	o-	0.1	0.4	0.4
	m-	0.0	0.0	0.0
	p-	1.4	1.6	1.0

^aThe theoretical estimates are from M06-2X/6-311G(d,p) computations with IEF-PCM solvation. The experimental kinetic data are from literature sources

^bFor the sources of the experimental kinetic data see ref (15) and references therein. Adapted from ref (15) with permission from the authors.